Electric current rectifier construction



A. GAUDENZl ET AL 1,865,512

ELECTRIC CURRENT RECTIFIER CONSTRUCTION Filed May 20, 1950 l/wentars Adhur Gaudenzi Ernst Kobe! Attomey Patented July 5, 1932 UNITED STATES PATENT OFFICE ARTHUR GAUDENZI, OF BAIDEN, AND ERNST KOBE-L, 0F ENNETBADEN, SWITZERLAND,

.ASSIGNORS T0 AKTIENGESELLSGHAFT BROWN BOVERI & CIE., OF BADEN, SWITZER- LAND, A JOINT STOCK COMPANY OF SWITZERLAND ELECTRIC CURRENT RECTIFIER CONSTRUCTION Application filed May 20, 1930, Serial No.

This invention relates to improvements in electric current rectifiers of the metallic vapor type used for power purposes and, particularly, to an improved cathode construction for such rectifiers.

If the operative surface of the liquid cathode, which is usually mercury, is made dependent on the amount of current flowing through the rectifier, the cathode spot is maintained at substantially a constant loca tion, thereby preventing heating of a large body of cathode material andthe consequent production of excessive quantities of vapor which leads to backfiring in the rectifier. Such restriction of the cathode spot may be obtained by the arrangement of a conical member of highly infusible and electrical 'non conductive material, such as quartz, within the cathodewell and connection of the conical member with a reservoir containing a piston controlled by the current in the rectifier. Movement of the piston varies the level and, therefore, the amount and the surface area of cathode material within the conical member. It is, however, possible that, when current densities sometimes encountered in rectifier operation and the relatively small area on which the heat produced is concentrated. It is, moreover, impossible to obtain suificient cooling of the amount of mercury involved so that it is impossible to obtain the desired reduction in the quantity of mercury vapor and, therefore, in the density of the mercury vapor within the rectifier.

It is, therefore, among the objects of the present invention to provide a cathode construction for electric current rectifiers in which the surfacearea and thequantity of the material serving as the cathode is dependent on the current flowing through the recti- Another object of the invention is to provide a cathode construction for electric cur- 453,951, and in Germany May 21, 1929.

through the rectifier controls the quantity of thereof which are not necessary to an understanding of the modification.

Referring more particularly to the drawing by characters of reference, the reference numeral 3 indicates a portion of the bottom of a metallic rectifier tank of the usual double wall construction and having an aperture thereto. A cylindrical insulating member l of suitable heat resisting and electrically non-conducting material in contact with the bottom 3 about the aperture forms a cathode well which is closed by a closure plate 6 preferably provided with an externally applied jacket 7 for the purpose of circulating a cooling medium therethrough.

The closureplate 6 is preferably formed with "an upwardly extending cylindrical wall arranged to receive a cathode basin member 8 having a conical shape at least interiorly thereof which basin is retained in the proper relation with theclosure plate by a plate of insulation 9 inserted between the basin 8 and the inwardly extending edge of the'basin 3 which insulation is formed to continue the internal conical contour of the basin.

The basin 8. is connected through a. tube 11 with a reservoir 12 containing a piston or provided with a flexible membrane operable, by an armature 13 upon energization of a coil 14 fromthe cathode current, to raise the 'mercury level and increase the surface area by forcing mercury up into the basin 8 or to permit the mercury levelin the basin to drop and the surface area to decrease due to the "return of the mercury to the reservoir. Any .mercury vaporized from thecathode and condensed on the cooled walls of'the rectifier "tank is collected in a channel 16 and returned through a suitable float valve 17 to the reservoir 12 thereby preventing sudden discharges of condensate and violent fluctuations and oscillations of the mercury in the reservoir.

It will be understood thatthe cathode closure plate may be made from either copper or iron and that the cathode basin may be of either a diiiicultly fusible metal such as tungsten, molybdenum, tantalium or the like, or may be made from a good heat-conducting material such as copper coated with a heatresistive material.

If the cathode closure plate is made of iron, a plate of copper may be inserted between the cathode closure plate and the cathode basin for the purpose of increasing the heat conductivity between the two. The cathode basin may likewise be made with a jacket for the purpose of circulating a cooling medium therethrough if increased cooling is desired.

The cathode basin may also be made, without any change in the spirit of the invention, from severalsegment-shaped members or sections, of difficultly fusible material, or it may be made from a readily fusible material having high heat-conducting properties with a coating of some diflicultly fusible metal. If the cathode basin is made out of separate sections of difiicultly fusible material, a cooling of the same by the use of a suitable cooling medium is practically impossible because of the difflculty of obtaining the proper vacuum-tight connections between the several portions.

Mercury may, however, still be used as a cooling fluid without providing special sealing means at all of the points of connections between the several portions making up the cathode basin. A very effective cooling of the cathode basin and its contents may be obtained either by circulating fluid mercury about the basin or by utilizing the vaporization of mercury about the basin as a means for abstracting the heat therefrom.

Fig. 2 shows one embodiment of a construction which may be used when the oathode basin is made of several portions or sec tions which are to be cooled by the circulation of a cooling medium and the vaporization of mercury about the exterior of the basin.

In such modified construction the basin 8 is again supported by the closure plate 6 which is formed to provide a considerable space about the basin 8 for the reception of mercury and to provide space for a coil of tubing 18 forming a path for the circulation of a cooling medium. The space between the closure plate 6 and the basin 8 is'connected with the interior space of the rectifier by a narrow passage 19 through the cooled rectifier bottom 3 so that vacuum-tight seals between the thermally stressed portions 8, 9 and the bottom 3 are not necessary. The heat produced in the interior of the cathode basin by the cathode spot is largely absorbed by the mercury vaporized on the exterior of the cathode basin and is thermo-dynamically transmitted, by the vapor produced therein, to the cooling coil 18. Since the cathode mercury surface in the interior of the cathode basin is kept very small, a fixing of the cathode spot and, accordingly, a uniform and very intensive impingement of the free mercury upper surface by the positive mercury ions is obtained so that the boiling point in the cathode basin is increased very greatly over the boiling point on the exterior thereof. It is thus possible to transfer at least a portion of the undesirable vaporization of mercury from the interior of the rectifier to the exterior thereof for the reason that such vaporization is used for the purpose of heat absorption.

Although but a few embodiments of the present invention have been illustrated and described, it will be apparent from the following that various changes may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

The invention claimed is:

1. In a construction for retaining the cathode material of an electric current rectifying device of the type having a metallic tank inclosing'a metallic vapor, the bottom of the tank having an aperture therethrough, a closure plate, an insulator spacing, said plate from the bottom of the tank, a basin havin an internal conical shape arranged upon said closure plate to retain a quantity of cathode material, and means communicating with said basin to vary the quantity of cathode material therein in dependence on the current flowing through the rectifier. I

2. In a construction for retaining the oathode material of an electric current rectifying device of the type having a metallic tank inclosing a metallic vapor, the bottom of the tank having an aperture therethrough, a metallic closure plate, a jacket forming a path for the circulation of a cooling medium therethrough arranged incontact with said plate, an insulator spacing said plate from the bottom of Said tank, a basin having a conical shape internally thereof and arranged upon said closure plate to retain a quantity of cathode material, and means communicating with said basin to vary the quantity of cathode material therein in dependence on the current flowing through the rectifier.

3. In a construction for retaining the cathode material of an electric current rectifying device of the type having a metallic tank inclosing a metallic vapor, the bottom of the tank having an aperture therethrough, a closure plate, an insulator spacing said plate from the bottom of the tank, a basin having aninternal conical shape arranged upon said closure plate to retain a quantity of cathode material, and means extending through said closure plate and communicating with the apex of said basin to vary the quantity of cathode material therein in dependence on the current flowing through the rectifier.

4. In a construction for retaining the cathode material of an electric current rectifying device of the type having a metallic tank inclosing a metallic vapor, the bottom of the tank having an aperture therethrough, a closure plate, an insulator spacing said plate from the bottom of the tank, a basin having a downwardly directed conical internal contour to retain a quantity of cathode material, said basin being supported upon and in contact with said closure plate, and means communicating with said basin to vary the quantity of cathode material therein in dependence on the current flowing through the rectifier.

5. In a construction for retaining the cathode .material of an electric current rectitying device of the type having a metallic tank inclosing a metallic vapor, the bottom of the tank having an aperture therethrough, a closure plate closing the aperture through the bottom of the tank, an insulator spacing said plate from the bottom of the tank, a basin having an internal conical shape arranged upon said closure plate to retain a quantity of cathode material, said basin being assembled from sections, said closure plate and said basin being arranged in spaced relation, a coil of tubing forming a path for the circulation of a cooling medium therethrough arranged in the space between said plate and said basin, and means communicating with said basin to vary the quantity of cathode material therein in dependence on the current flowing through the rectifier.

6. In a construction for retaining the cathode material of an electric current rectitying device of the type having a cooled metallic tank inclosing a metallic vapor, the bottom of the tank having an aperture therethrough, a closure plate forsaid aperture, an insulator spacing said plate from the bottom of the plate, a basin having an internal conical contour with a downwardly directed apex to retain a quantity of cathode material, means communicating with the apex of said basin to vary the quantity of cathode material therein in dependence on the current flowing through the rectifier, and means for collecting and returning the metallic vapor condensed on the walls of the tank to said means communicating with said basin. 7

7. In an electric current rectifier comprising a container having an aperture therethrough, a closure plate for said aperture, an insulator spacing said plate from said container, a basin having an internal conical contour arranged on said plate to retain a quan tity of cathode material, and means effective to increase the quantity of cathode material within said basin in dependence upon increase in flow of current through the rectifier.

8. In an electric current rectifier comprising a container having an aperture therethrough, a closure plate for said aperture, an insulator spacing said plate from the said container, a basin having an internal-conical contour arranged on said plate to retain a quantity of cathode material, and means eftective to decrease the quantity of cathode material within said basin in dependence upon decrease in flow of current through the rectifier.

9. In an electric current rectifier comprising a container, having an aperture therethrough, a closure plate for said aperture, an insulator spacing said plate from the said container, a basin having an internal conical contour arranged on said plate to retain a quantity of cathode material, and means efof current through the said rectifier and means.

11. In an electric current rectifier, the combination with a metallic container having an aperture therethrough, a basin of refractory metallic material arranged to retain a quantity of cathode material, the said basin being disposed to close the said aperture, of means disposed external to the said container and external to said basin operative to cause in crease in the quantity of cathode material within the said basin upon increase in flow of current through the rectifier.

12. In an electric current rectifier, the combination with a metallic container having an aperture therethrough, a basin of re- .fractory metallic material arranged to retain a quantity of cathode material, the said basin being insulated from the said container and disposed to close the said aperture, of means disposed external to the said container and external to the said basin operative to cause increase in the quantity of cathode material within the said basin upon increase in flow of current through the said rectifier.

13. In an electric current rectifier, the combination with a metallic container having an aperture therethrough, a closure plate for said aperture, an insulator spacing said plate from the said container, and a basin of refractory metallic material arranged to receive and retain a quantity of cathode material, the said basin being arranged on said plate and electrically insulated from the said container, of means external to said basin and external to said container operative in dependence upon flow of current through V the said rectifier to cause an increase in the quantity of cathode material Within the said 0 basin upon an increase in flow of current through the rectifier.

14. In an electric current rectifier, the combination With a container having an aperture therethrough, and a basin arranged to retain a quantity of cathode material and to close said aperture, of electro-magnetic means efiective to Vary the quantity of cathode material Within the said basin, the said means being operative in dependence upon the flow of current through the rectifier.

In testimony whereof We have hereunto subscribed our names this 5th day of May A. D. 1930.

ARTHUR GAUDENZI.

ERNST KOBEL. 

